The invention relates to a fin for a heat exchanger, consisting essentially of a matrix of tubes and of fins disposed transversely to the latter, said fins having pass-through elements to receive tubes which are to be joined mechanically, while a first, preferably liquid medium flows through the tubes and the fins are acted on by a second, preferably gaseous medium and are positioned in their fin pitch by integral spacers.
Heat exchanger fins are known from DE-A-37 28 969 and also from DE-C-34 23 746. The power of a heat exchanger is governed, among other factors, by its fin density or so-called fin pitch (number of fins per decimeter), and to ensure uniform quality this predetermined fin density must therefore be accurately maintained, for which reason spacers intended to position the fins on the tubes are provided. Such spacers can be formed either as tabs produced from the fin sheet, which then also serve as turbulence producers, or by bent-over contact surfaces attached at the ends of the pass-through elements of the fins.
In the case of DE-A '969 these contact surfaces are in the form of tongues distributed over the periphery, while in the case of DE-C '746 they are sickle-shaped contact surfaces arranged on the longer sides of the ellipses. In such arrangements it may be a disadvantage that, when the tubes are expanded in relation to the pass-through elements of the fins, complete contact is no longer ensured between the pass-through element and the tube. In addition, the bending-over of the contact surfaces constitutes an additional operation after the formation of the pass-through elements.